1. Field of the Invention
The invention relates to compositions and methods effective for control of social insects such as termites, fire ants, and cockroaches.
2. Description of the Prior Art
Cotton plants, especially the seed, are a rich source of gossypol and related terpenes. Cotton is a major cash crop of the Southern states of the U.S. Cotton seed (a by-product) with an annual production of 7 million tons in the U.S. and 36 million tons worldwide, has long been processed into edible oil and protein feed meals. Due to the presence of gossypol, a known antinutritional factor to nonruminant animals, the protein meals are primarily used as feed to ruminants. Processing technologies (Gardner, H. K., et al., xe2x80x9cAdvanced liquid cyclone process for edible cotton seed flour production,xe2x80x9d [1973]E. Oil Mill Gaz. 78:12-17; Freeman et al., xe2x80x9cAdvanced air classification of defatted, glanded cotton seed flours to produce edible protein product,xe2x80x9d [1979]J. Food Sci. 44:1522-1524) have been developed at the U.S. Department of Agriculture to reduce the concentration of gossypol in the finished meal. A cotton seed meal produced by these processes can be used as a food ingredient as long as it contains no more than 450 ppm free gossypol, a limit established by the research effort of the Southern Regional Research Center, ARS-USDA, New Orleans, La. (Code of Federal Regulations 21.172.894).
Glandless cultivars, through conventional breeding, are subject to attack by beet armyworm (Spodoptera exigua [Hubner]), bollworm (Heliothis zea [Boddie]), grape colaspis (Maecolaspis flavida [Say]), cutworms (undetermined species), and pill bugs (Porcellio spp.). Rodents also attacked glandless bolls and ate glandless cotton seed more aggressively than the glanded seed as (Bottger et al., xe2x80x9cRelation of gossypol content of cotton plants to insect resistance,xe2x80x9d [1964] J. Econ. Entomol. 57:283-285). Gossypol is also toxic to cotton aphids (Aphis gossypii Glover), lygus bugs (Lygus hesperas Knight), salt-marsh caterpillars (Estigmene acrea [Drury]), thurberia weevils (Anthonomus grandis thurberiae Pierce), and bollworms (Bottger et al., 1964, supra). Jenkins et al. (xe2x80x9cThe comparative preference of insects for glanded and glandless cottons,xe2x80x9d [1966] J. Econ. Entomol. 59:352-356), showed that grape colaspis and leaf beetle (Gastrophysa cyanea Melsheimeriae) preferred feeding on glandless compared to glanded cotton cultivars, and cotton leafworm moths (Alabama argillacea [Hubner]) preferred to oviposit on glandless lines.
In addition to gossypol, several other toxic terpenoids (generally referred to as terpenoid aldehydes) are found in the glands in foliar tissue of cotton plants, including p-hemigossypolone, p-hemigossypolone-6-methyl ether, heliocide H1, heliocide H2, heliocide H3, heliocide H4, heliocide B1, heliocide B2, heliocide 3, and heliocide B4.
The effective dosage (xcexcmoles/g diet) of toxic terpenoids required to reduce by 50% the growth of the tobacco budworm (Heliothis virescens [F.]) larvae fed an artificial diet have been determined for several of these compounds as follows: heliocide H1, 2.5; heliocide H2, 11.2; heliocide H3, 3.9; heliocide B1, 4.6; hemigossypolone, 10.5; and gossypol, 0.8 (Stipanovic et al., xe2x80x9cNatural insecticides from cotton (Gossypium)xe2x80x9d, [1977] ACS Symposium Series, No. 62, Host Plant Resistance to Pests, 197-214). Hemigossypolone-6-methyl ether and heliocides B2 and B3 had no effect on growth at 2.5 xcexcmoles/g diet. In this study, gossypol was the most toxic compound with heliocides H1 and H3 a close second and third. Conversion to the 6-methyl ether derivative consistently reduced toxicity. In contrast, field studies have shown that the levels of heliocides and hemigossypolone correlate better with resistance than the gossypol levels (Hedin, P. A. et al., xe2x80x9cRelationship of glands, so cotton square terpenoid aldehydes and other allelochemicals to larval growth of Heliothis virescens [Lepidoptera: Noctuidae],xe2x80x9d [1992] J. Econ. Entomol. 85:359-364; Jenkins, J. N., xe2x80x9cHost resistance to insects in cotton,xe2x80x9d [1995] in Proceedings of the World Cotton Research Conference-1, edited by G. A. Constable and N. W. Forrester, Melbourne, Australia, pp. 359-372).
In addition to the terpenoid aldehydes, the volatile mono- and sesquiterpenes also occur exclusively in the foliar glands. Damaged glandless plants can also produce terpenes, but in much smaller amounts. The volatile terpene caryophyllene oxide interacts synergistically with gossypol to retard tobacco budworm larval growth (Gunasena et al., xe2x80x9cEffects of caryophyllene, caryophyllene oxide, and their interaction with gossypol on the growth and development of Heliothis virescens [F.][Lepidoptera: Noctuidae],xe2x80x9d [1988] J. Econ. Entomol. 81:93-97; Williams et al., xe2x80x9cEffects of gossypol and other cotton terpenoids on Heliothis virescens development,xe2x80x9d [1987]Rev. Latinoamer. Quim. 18:119-131), but the related sesquiterpene caryophyllene does not act synergistically. When glands are eaten, insects consume the terpenoid aldehydes along with a diverse mixture of monoterpenoids.
Several other low molecular weight compounds and condensed tannins have been implicated as possible factors in insect resistance. Hedin et al. (xe2x80x9cCyanidin-3 xcex2-Glucoside, a newly recognized basis for resistance in cotton to the tobacco budworm Heliothis virescens (Fab.),xe2x80x9d [1983]Experientia 39:799-801), have identified cyanidin-3xcex2-glucoside in the glands. This and various other allelochemicals (i.e., condensed tannins, flavonoids, and cyclopropene fatty acids) have been evaluated for their effect on bollworms and budworms (Shaver, T. N. and Lukefahr, M. J., xe2x80x9cEffects of flavonoids pigments and gossypol on growth and development of the bollworm, tobacco budworm, and pink bollworm,xe2x80x9d [1969] J. Econ. Entomol. 62:643-646; Elliger et al., xe2x80x9cRelative toxicity of minor cotton terpenoids compared to gossypol, xe2x80x9d [1978] J. Econ. Entomol. 71:161-164; Chan et al., xe2x80x9cInhibition of lepidopterous larval growth by cotton constituents,xe2x80x9d [1978] Entomol. Exp. Appl. 24:94-100; Chan et al., xe2x80x9cCondensed tannin, an antibiotic chemical from Gossypium hirsutum,xe2x80x9d [1978] J. Insect Physiol. 24:113-118; Chan et,al., xe2x80x9cA rapid diet preparation method for antibiotic phytochemical bioassay,xe2x80x9d [1978] J. Econ. Entomol. 71:366-368; Hedin et al., xe2x80x9cThe chemical basis for resistance in cotton to Heliothis insects,xe2x80x9d [1981] In Regulation of Insect Development and Behavior, M. Kloza, Ed., Wroclaw Univ. Press, pp. 1071-1086; Hedin et al., xe2x80x9cEffects of cotton plant allelochemicals and nutrients on behavior and development of tobacco budworm,xe2x80x9d [1991] J. Chem. Ecol. 17:11-7-1121; Jenkins et al., xe2x80x9cCotton allelochemicals and growth of tobacco budworm larvae,xe2x80x9d [1983] Crop Sci. 23:1195-1198). These compounds also can play a role in insect resistance. Reports in the literature comparing glandless and glanded plants may refer to the gossypol content of the latter, but actually refer to all of the terpenoid aldehydes in the gland. Cotyledonary leaves are an exception, since the terpenoid aldehyde present in this tissue is almost exclusively gossypol.
Bollworms and tobacco budworms grow better on glandless than on glanded cottons. However, differences in infestations of cotton fleahoppers (Psallus seriatus [Reuter]) and the boll weevil (Anthonomus grandie Boheman) between glanded and glandless plants were small or non-existent. Lukefahr and Martin (1966), supra, found that gossypol was equally toxic to bollworm and tobacco budworm larvae. Bottger, G. T. and Patana, R. (xe2x80x9cGrowth, development, and survival of certain lepidoptera fed gossypol in the diet,xe2x80x9d [1966] J. Econ. Entomol. 59:1166-1168), found the beet armyworm, bollworm, cabbage looper (Trichoplusiani [Hxc3xcbner]) and salt-marsh caterpillar grew slower on diets containing gossypol acetate. Gossypol appears to deter many lepidopterous pests of cotton.
Spiny bollworm (Earias insulana Boisduval), which is a major cotton pest in Israel, also causes more damage on glandless cottons in the field (Meisner et al., xe2x80x9cThe effect of gossypol on the larvae of the spiny bollworm, Earias insulana,xe2x80x9d [1977] Ent. Exp. and Appl. 22:301-303). In bolls containing 0.58% gossypol, 45% pupated, but at 2.34% gossypol, only 9% pupated. Dongre, T. K. and Rahalkar, G. W. (xe2x80x9cGrowth and development of spotted bollworm, Earias vittella on glanded and glandless cotton and on diet containing gossypol,xe2x80x9d [1980] Entomol. Exp. and Appl. 27:6-10) found similar results with the spotted bollworm. Feeding on glandless cotton leaves treated with a 1% gossypol solution gave similar results. With the cotton leafworm (Spodoptera littoralis [Boisduval]), the effect was even more dramatic (Meisner, J. et al., xe2x80x9cPhagodeterrency induced by pure gossypol and leaf extracts of a cotton strain with high gossypol content in the larva of Spodoptera littoralis,xe2x80x9d [1977] J. Econ. Entomol. 70:149-150; Meisner, J. et al., xe2x80x9cThe response of Spodoptera littoralis larvae to gossypol incorporated in an artificial diet,xe2x80x9d [1977] Environ. Entomol. 6:243-244; Meisner, J. et al., xe2x80x9cThe response of Spodoptera littoralis larvae to gossypol incorporated in an artificial diet,xe2x80x9d [1977] Environ. Entomol. 6:243-244). With 0.5% gossypol in the diet, mortality was nearly 70% after 10 days and only 0.3% of the larvae eventually pupated; 1.0% gossypol strongly suppressed feeding (Meisner, J. et al., xe2x80x9cThe response of Spodoptera littoralis larvae to gossypol incorporated in an artificial diet,xe2x80x9d [1977] Environ. Entomol. 6:243-244). Larval growth and development of the native budworm (Heliothis punctigera Wallengren) and the cotton bollworm Heliothis armigera (Hxc3xcbner) are also inhibited by gossypol (Kay, I. R. et al., xe2x80x9cThe effect of gossypol in artificial diet on the growth and development of Heliothis punctigera Wallengren and H. armigera (Hxc3xcbner) (Lepidoptera: Noctuidae),xe2x80x9d [1979] J. Aust. Ent. Soc. 18:229-232).
Gossypol has an antifeedant effect. Shaver and Parrott found development was less affected by gossypol when larvae were allowed to first feed on standard diet (Shaver, T. N. and Parrott, W. L., xe2x80x9cRelationship of larval age to toxicity of gossypol to bollworms, tobacco budworms, and pink bollwormsxe2x80x9d [1970] J. Econ. Entomol. 63:1802-1804). Older larvae were either less deterred from eating or were better able to detoxify the gossypol. Shaver et al. (xe2x80x9cFood utilization, ingestion, and growth of larvae of the bollworm and tobacco budworm on diets containing gossypol,xe2x80x9d [1970] J. Econ Entomol. 63:1544-1546) showed that bollworms (5-day-old) utilized a high glanded diet less efficiently than low glanded or glandless diets, and growth was retarded. A diet containing an acetone extract from the high glanded cultivar was also utilized less efficiently and there was a decrease in larval weight. With bollworms, at 0.15% gossypol, in an artificial diet, food utilization by the bollworm was decreased from 54.5% on the regular diet to 42.5% on the gossypol diet. With tobacco budworms, gossypol at the 0.15% level did not measurably affect food utilization. However, when the level was increased to 0.30%, food consumption of both 5- and 8-day-old larvae was impaired.
Oliver et al. conducted studies to determine how glanded and glandless cotton flower buds (squares) were utilized by the bollworm (Oliver, B. F. et al., xe2x80x9cUtilization of glanded and glandless cotton diets by the bollworm,xe2x80x9d [1970] J. Econ. Entomol. 63:1965-1966). They studied four stages of larvae that were first raised on a control diet. Larvae that weighed approximately 60, 110, 150, or 192 mg were placed on diets containing freeze-dried squares. Larvae were allowed to feed for 48 hours. All four sizes of larvae gained less weight when transferred to the glanded diet, and they consumed 20-31% less diet. Growth of the smallest was most inhibited due to a reduced efficiency of food conversion to body mass. The efficiency of food conversion for larvae of different weights compared to larvae on glandless diets was as follows: 60 mg, 51%; 120 mg, 64%; 150 mg, 82%; and 198 mg, 97% as efficient. Thus, both a reduction in food consumption and in efficiency of food conversion were responsible for the reduced weight gain. The higher efficiency of food conversion of older larvae explains the 1970 report by Shaver and Parrott on the modest effect of gossypol on older larvae. Further studies in 1987 by Parrott et al. showed that tobacco budworm neonate larvae fed gossypol at 0.02% in an artificial diet for nine days were only slightly smaller (98%) than the control (Parrott, W. L. et al., xe2x80x9cFeeding and recovery of gossypol and tannin from tobacco budworm larvae,xe2x80x9d [1987] Southwest. Entomol. 12:197-204). However, at 0.06% and 0.2% gossypol in the diets, the weights were only 63% and 13% of the controls, respectively. Essentially no gossypol could be recovered from any of the larvae themselves at any dietary level.
Mulrooney et al. found the efficiency of conversion of digested food to body weight was lower for tobacco budworm in cultivars with higher levels of gossypol, implying that energy is being diverted for detoxification processes (Mulrooney, J. E. et al., xe2x80x9cNutritional indices of second-instar tobacco budworm larvae [Lepidoptera: Noctuidae] fed different cotton strains,xe2x80x9d [1985] J. Econ. Entomol. 78:757-761).
Glands have a similar effect on the cotton leafworm (A. argillacea) (Johnson, S. J., xe2x80x9cLarval development, consumption, and feeding behavior of the cotton leafworm, Alabama argillacea (Hxc3xcbner),xe2x80x9d [1984] Southwest. Entomol. 9:1-6).
In a related study, Rojas et al. (1992) studied the metabolic fate of radiolabelled 14C gossypol in the tobacco budworm diet (Rojas, M. G. et al., xe2x80x9cMetabolism of gossypol by Heliothis virescens [F.] [Lepidoptera: Noctuidae],xe2x80x9d [1992] Envir. Entomol. 21:518-526; Rojas, M. G. et al., xe2x80x9cA method for the preparation of labelled gossypol by the incorporation of 14C Acetate,xe2x80x9d [1989] J. Labelled Comp. Radiopharm. 27:995-998). The radioactivity was mainly found in the fat body of fifth-stadium larvae, the dissolved tissues of pupae, the abdomen of newly-emerged moths, and the larval frass. Labeled gossypol was eliminated as a respiration product from third to fifth instars, and from prepupa to adult. Gossypol was excreted in the larval frass as a free compound and as a conjugate. High-performance liquid chromatography (HPLC) analyses of the radiolabelled frass indicated that the ethyl acetate and methyl alcohol extracts contained the highest concentrations of free and conjugated gossypol, respectively. Two metabolites from the tobacco budworm larval frass were isolated and identified as derivatives of gossypol containing six glucose moieties attached to the gossypol nucleus, and a derivative of methyl parasept (diet preservative) containing one glucose moiety (Rojas, M. G. et al., xe2x80x9cA detoxification product of the xenobiotic methyl parasept by Heliothis virescens [F.] [Lepidoptera: Noctuidae],xe2x80x9d [1990] Comp. Biochem. Physiol. 96C:281-285). This suggests that for the specialist feeder, excretion is the preferred method of elimination, rather than detoxification. Gossypol may be toxic to both insects, but the cotton leafworm more efficiently excretes gossypol. Thus, the harmful effects are minimized and the energy required to detoxify it is less.
Meisner et al. (1978) found that gossypol inhibits protease and amylase activity, but does not affect invertase activity in the cotton leafworm (S. littoralis) (Meisner, J. et al., xe2x80x9cGossypol inhibits protease and amylase activity of Spodoptera littoralis larvae,xe2x80x9d [1978] Ann. Entomol. Soc. Amer. 71:5-8). Gossypol appeared to interact with both the enzyme substrate (i.e., casein) and with the protease enzyme. They concluded that either or both mechanisms could account for gossypol""s activity.
Studies by Hedin et al. (1988) strongly support the concept that gossypol acts as both a toxicant and an antifeedant, especially in the early instars (Hedin, P. A. et al., xe2x80x9cElucidating mechanisms of tobacco budworm resistance to allelochemicals by dietary tests with insecticide synergists,xe2x80x9d [1988] Pest. Biochem. Physiol. 32:55-61). They studied the interaction of gossypol with piperonyl butoxide, an insecticide synergist that enhances insecticidal action by inhibiting the insect""s mixed function oxidases (MFOS). Gossypol alone reduced the growth of all these groups of larvae. When piperonyl butoxide was added to the gossypol, the larvae were significantly smaller than with the gossypol alone. Since piperonyl butoxide at 0.02% in the diet had little effect on larval growth, the authors concluded that MFOs are probably involved. They also concluded that gossypol probably acts as an antifeedant, especially in the early instars. Williams et al. (1987), supra, report the same reduction in feeding by tobacco budworm first instar larvae and a synergistic. effect when gossypol is combined with caryophyllene oxide.
Several studies support the concept that gossypol acts as an antifeedant to early instars (Waiss, A. C. et al., xe2x80x9cBiological active cotton constituents and their significance in host plant resistance,xe2x80x9d [1981] Proc. Beltwide Cotton Prod. Res. Conf., New Orleans, La., p. 61; Parrott, W. L. et al., xe2x80x9cFeeding behavior of first-stage tobacco budworm [Lepidoptera: Noctuidae] on three cotton cultivars,xe2x80x9d [1983] Ann. Entomol. Soc. Amer. 76:167-170); Hedin et al. [1992], supra).
Raulston et al. (1985) observed a significant increase in budworm tolerance to gossypol during thirteen generations (Raulston, J. R. et al., xe2x80x9cTobacco budworms: response to gossypol and selection in a field-collected strain under laboratory conditions,xe2x80x9d [1985] J. Econ. Entomol. 78:158-162).
Vilkova et al. (1989) reported that even though high gossypol lines had a detrimental effect on cotton bollworm development, survival and larval weight when compared to those on low gossypol lines, the larvae from the high gossypol lines that survived had a higher pupal weight because of their apparent resistance to gossypol, but fecundity of these survivors was significantly reduced (Vilkova, N. A. et al., xe2x80x9cEffect of cotton cultivars with high content of goeBypol on development of the cotton bollworm, Heliothis armiqera [Hbn.][Lepidoptera: Noctuidae],xe2x80x9d [1989] Entomol. Rev. 68:129-137).
Several studies suggest that gossypol induced resistance to insecticides. Abou-Donia et al. (1974) found that topical treatment of a solution of gossypol in acetone to fourth instar larvae of the cotton leafworm (S. littoralis) increased the LD50 dosage from two to three times the LD50 for untreated larvae for four different insecticides (Abou-Donia, M. B. et al., xe2x80x9cGossypol: antagonistic effect on toxicity of insecticides to Spodoptera littoralis,xe2x80x9d [1974] Experientia 15:1151-1152). In an artificial diet study, gossypol concentrations were negatively correlated with the toxicity of methyl parathion to budworm larvae (Shaver, T. N. and Wolfenbarger, D. A., xe2x80x9cGossyol: influence on toxicity of three insecticides to tobacco budworm,xe2x80x9d [1976] Environ. Entomol. 5:192-194). When leaves of a high gossypol plant were treated with phosfolan, mortality of cotton leafworm larvae was lower compared to a glandless cultivar (Meisner et al., xe2x80x9cThe response of Spodoptera littoralis larvae to gossypol incorporated in an artificial diet,xe2x80x9d [1977] Environ. Entomol. 6:243-244).
Biosynthesis of terpenoids related to gossypol are induced in cotton when it is attached by various fungal pathogens (Daayf, F. M. et al., xe2x80x9cEarly vascular defense reactions of cotton roots infected with a defoliating mutant strain of Verticillium. dahliae,xe2x80x9d [1997] Euro. J. Plant Path. 103:125-136; Cui, Y. et al., xe2x80x9cExpression of potential defense response genes in cotton,xe2x80x9d [2000] Physiol. Mol. Plant Path. 56:25-31). Insect damage appears to induce chemical changes in the foliage and induction of volatile terpenes (Loughrin, J. H. et al., xe2x80x9cDiurnal cycle of emission of induced volatile terpenoids by herbivore-injured cotton plants,xe2x80x9d [1994] Proc. Nat""l Acad. Sci. 91:11836-11840; McCall, P. J. et al., xe2x80x9cHerbivore-induced volatile emissions from cotton [Gossypium hirsutum L.] seedlings,xe2x80x9d [1994] J. Chem. Ecol. 20:3039-3059; Donath, J. and Boland, W., xe2x80x9cBiosynthesis of acyclic homoterpenes: enzyme selectivity and absolute configuration of the nerolidol precursor,xe2x80x9d [1995] Phytochemistry 39:785-790; Rose, U. S. R. et al., xe2x80x9cVolatile semiochemicals released from undamaged cotton leaves,xe2x80x9d [1996] Plant Physiol. 111:487-495; Pare, P. W. and Tumlinson, J. H., xe2x80x9cCotton volatiles synthesized and released distal to the site of insect damage,xe2x80x9d [1998] 47:521-526).
Alborn et al. (1996) reported that the beet armyworm larvae prefer young undamaged leaves to undamaged young leaves from a previously damaged plant (Alborn, H. T. et al., xe2x80x9cSystemic induction of feeding deterrents in cotton plants by feeding of Spodoptera Spp. larvae,xe2x80x9d [1996] J. Chem. Ecol. 22:919-932). See also, McAuslane, H. J. et al., xe2x80x9cSystemic induction of terpenoid a aldehydes in cotton pigment glands by feeding of larval Spodoptera exigua,xe2x80x9d (1997) J. Chem. Ecol. 23:2861-2879. HPLC analysis revealed higher concentrations of hemigossypolone and heliocides H1 and H2 per gland in foliage of these damaged plants. When compared to leaves from undamaged plants, heliocide H2 showed the largest change with over a three-fold increase in concentration.
In 1998, McAuslane and Alborn found a 33-fold increase in preference for undamaged terminal leaves from undamaged glanded plants by beet army worm larvae (McAuslane, H. J. and Alborn, H. T., xe2x80x9cSystemic induction of allelochemicals in glanded and glandless isogenic cotton by Spodoptera exigua feeding,xe2x80x9d [1998] J. Chem. Ecol. 24:399-416). Extracts from the terminal foliage contained significantly higher concentrations of hemigossypolone, gossypol and the heliocides. Of these compounds, heliocides H1 and H4, which are derived from the reaction of hemigossypolone and xcex2-ocimene, had the largest percentage increase, 351% and 487% respectively. Hemigossypolone had an increase of 149%, gossypol increased by 124%and heliocides H2 and H3 increased by 42%and 45%, respectively. They also noted an increase in volatile compounds from the damaged plants. Among the monoterpenes, xcex2-ocimene and myrcene had the largest increases of greater than six-fold and four-fold, respectively; these compounds react with hemigossypolone to give heliocides H1 and H4, and heliocides H2 and H3, respectively. xcex1-Pinene, xcex2-pinene and limonene increased by 3.2-3.6-fold. Damaged glanded plants released more than twice as many terpenes as undamaged plants.
Gossypol is largely excreted in the bound form, and thus decreases the nutritional value of the plant material. Studies with non-ruminant animals have shown that gossypol binds to free amino groups in proteins such as in lysine and thereby reduces the nutritional value of the feed. The same appears to be true for the budworm (Meisner et al. [1978]; supra). Terpenoid aldehydes did not increase in wounded tissue itself.
Gossypol does not appear to provide the plant with any protection from boll weevil (Lukefahr, M. J. et al., xe2x80x9cGrowth and infestation of bollworms and other insects on glanded and glandless strains of cotton,xe2x80x9d [1966] J. Econ. Entomol. 59:817-820). Parrott et al. (1969) concluded boll weevils seemed to be attracted to and feed on plants that contain gossypol (Parrott, W. L. et al., xe2x80x9cPreference studies with hosts and nonhosts of the boll weevil, Anthonomus grandis,xe2x80x9d [1969] Ann. Entomol. Soc. Amer. 62:261-264). Gossypol and caryophyllene both suppress bacteria in the boll weevil""s gut and egg hatch of boll weevils reared on a diet containing gossypol was improved over those reared on a diet without gossypol (Hedin, P. A. et al., xe2x80x9cSuppressants of gut bacteria in the boll weevil from the cotton plant,xe2x80x9d [1978] Econ. Entomol. 71:394-396).
Davidson et al. (1996) found gossypol did not affect mortality or honeydew production of silverleaf whitefly (Bemisia argentifolii Bellows and Perring) (Davidson, E. W. et al., xe2x80x9cActivity of natural toxins against the silverleaf whitefly Bemisia argentifolil, using a novel feeding bioassay system,xe2x80x9d [1996] Entomol. Exper. Appl. 79:25-32). Almeida (1980) suggested that there appears to be an optimum value of gossypol for normal development of cotton strainer bug (Dysdercus fasciatus Signoret) (Almeida, A. A., xe2x80x9cInfluence of the glandless and glanded cotton seeds on developmentxe2x80x9d, fecundity and fertility of Dysdercus fusciatus signoret [Hemiptera Pyerhocoridae] [1980] Rev. Brasil. Biol. 40:659-662).
Karban and Carey (1984) found that spider mite (Tetranychus urticae Koch) populations were reduced on new growth of cotton seedlings whose cotyledonary leaves had previously been exposed to mites, as compared to plants that had never been exposed to mites.
Gossypol acts as a male antifertility agent in humans en and adversely affects a host of enzymes. These various toxicological/biological effects in animals are due primarily or perhaps exclusively to the (xe2x88x92)-enantiomer of gossypol.
Baiting compositions not containing gossypol for controlling termites are known, as described in U.S. patent application Ser. Nos. 09/625,940 filed Jul. 26, 2000, Ser. No. 09/294,499 filed Apr. 20, 1999, and Ser. No. 09/748,036 filed Dec. 22, 2000, the contents of each of which are incorporated herein by reference.
We have discovered that low concentrations of gossypol and related phyllophage toxins from cotton improve the effectiveness of insecticidal agents against social insects, including cockroaches, and particularly termites and ants. Levels of gossypol and other cotton phyllophage toxins which are sufficiently low as to be non-biocidal to social insects alone, will significantly increase the control efficacy or activity of other insecticidal agents. Consequently, use of these low levels of these cotton phyllophage toxins allows the levels of insecticidal agents necessary for effectively controlling the insects to be significantly reduced relative to applications without cotton phyllophage toxins. Furthermore, insecticidal agents which are normally ineffective for control of social insects when used alone, may be effective when used in conjunction with the cotton phyllophage toxins. Low, non-biocidal concentrations of gossypol or the other cotton phyllophage toxins may be formulated into a bait, alone or in combination with the other insecticidal agents. Alternatively, the other insecticidal agents may be formulated into separate baits which are applied in the vicinity of the gossypol or cotton phyllophage toxin containing bait, such that both baits are subject to consumption by the target insects.
In accordance with this discovery, it is an object of this invention to provide compositions and methods for controlling social insects.
Another object of this invention is to provide compositions and methods for controlling termites, ants, or cockroaches.
It is also an object of the invention to provide compositions and methods for controlling social insects such as termites, ants, and cockroaches using reduced levels of insecticides.
Other objects and advantages of this invention will become readily apparent from the ensuing description.